Birds raised for commercial reasons (e.g., chickens, turkeys, geese, guinea fowl, ducks, etc.) are often vaccinated to treat and/or prevent infections, disease, etc. Apparatus and methods for administering vaccine to large numbers of birds are described in a variety of patent documents such as U.S. Pat. No. 4,449,968 (Peterson); U.S. Pat. No. 4,850,997 (DuBose); U.S. Pat. No. 4,177,810 (Gourlandt); U.S. Pat. No. 5,312,353 (Boggess et al.); U.S. Pat. No. 6,565,533 B1 (Smith et al.).
Many of the apparatus and methods described in these documents rely on injection (e.g., subcutaneous, intramuscular, etc.) of the vaccine. Injection of vaccines is desirable because of the ability to deliver known, controllable dosage amounts to each bird. Injection delivery does, however, have a number of disadvantages. For example, cross-contamination between birds can be an issue if the same injection device (e.g., needle, etc.) is used for multiple birds. A potentially larger issue is the cost required to accurately deliver the injection, i.e., each bird must typically be individually restrained to ensure accurate delivery of the desired dose. Restraint can also be important to reduce the chance that the type of injection (e.g., subcutaneous, intramuscular, etc.) is improperly performed. In spite of such measures, however, birds can, e.g., receive an intramuscular injection when a subcutaneous injection is desired or vice versa. Such misdelivery of vaccines can negatively impact their efficacy.
One approach to addressing the problems associated with injection delivery methods is the use of spray equipment to deliver vaccines to groups of birds (U.S. Pat. No. 4,449,968 (Peterson); U.S. Pat. No. 4,850,997 (DuBose)). Such an approach has a number of drawbacks such as, e.g., the inability to accurately control dosage to each bird, misdelivery of vaccines (e.g., where the vaccine is inhaled when inhalation is not desired), excessive waste (for the vaccine that is not delivered to any bird, etc.).
Another approach to the vaccine delivery problem involves the use of a dropper to deliver a vaccine-laden drop into the eye of a bird restrained for other purposes (e.g., debeaking, etc.). This approach raised problems such as accuracy in the dosage delivered (e.g., if the drop missed the bird's eye due to anatomical variations, etc.), speed of the delivery (e.g., premature release of the bird may result in loss of significant amounts of the vaccine before it is irreversibly delivered to the bird), etc.
Another approach to vaccine delivery involves spraying vaccine into the mouth of a bird when restrained for another purpose (e.g., debeaking, etc.). Problems encountered with this approach included secondary bacterial infections in the lungs (potentially leading to death), and the incompatibility of many vaccines with oral delivery.